HDAC9 and schizophrenia: Moreover, cultured PBMC were found to be capable of demonstrating the lack of “plasticity” in schizophrenia chromatin structure discovered in the in vivo study, in that we found less change in GAD67 mRNA expression, H3K9me2 levels, and acetylated histone 3 levels in PBMC cultured with an HDAC inhibitor compared to nonpsychiatric controls [10, 12].